FIG. 5.

Polyclonal antibody UVT70 labels a prerhoptry compartment in developing daughter parasites. (A) Schematic representation of T. gondii endodyogeny, a process in which two daughter parasites are formed within an intact mother parasite. Red, inner membrane complex of the mother and daughter parasites; light green, rhoptries of the mother parasite; bright green, daughter rhoptries. (B) Dual-label immunofluorescence microscopy. The inner membrane complex (MAb 45.15) of the mother and daughter parasites is red, and the UVT70-positive compartment is green in the merged images. The compartment labeled by UVT70 is located immediately anterior to the nucleus and posterior to the rhoptries in developing daughter parasites from the initial stages (a) to very late in endodyogeny (g). UVT70 labeling disappears immediately prior to the budding of the daughters from the mother (i), and no labeling is detectable in mature, extracellular parasites (not shown). Corresponding differential interference contrast images are shown below. Bar, 10 μm. (C) Immunoelectron microscopy with polyclonal antibody UVT70. In parasites undergoing endodyogeny, UVT70 localizes to electron-dense vesicles in the daughter parasites, as is evident from the distribution of the 6-nm immunogold particles. N, mother nucleus; IMC, daughter inner-membrane complexes. Bar, 500 nm. Inset, enlargement of the boxed region.